1. Field of the Invention
The present invention relates to splicing apparatus, and in particular, it relates to apparatus used for supporting multi-strand large diameter electric cable during splicing.
2. Description of the Prior Art
In the past, large diameter multi-conductor cables have been a problem to splice. One use of large diameter multi-conductor cables is to supply electric power to large drag lines and other equipment used in open pit mines. The drag lines include a number of electric motors that consume large quantities of electric power. Typically, the cables have a diameter of two to four inches and include three one-inch solid copper conductors, with a couple of half-inch diameter ground conductors and a control wire that interrupts the flow of electricity if the cable is damaged. Generally, the cables are used in 1,000 foot lengths and are laid on the ground with one end being connected to a substation and the other end being connected to the drag line.
Since the multi-conductor cables lie on the ground, the cable occasionally is damaged by a piece of machinery, such as a bulldozer running over the cable. When the cable is damaged, the control wire shuts down the substation and stops the power flow to the drag line. The cable must then be immediately repaired or replaced to avoid the cost of an idle drag line.
One prior art method of repairing large diameter multi-conductor cables includes cutting the cable at the damaged spot and peeling back the insulation, including the insulation around the conductors, ground wires and control wire at each end of the cut cable. The individual conductors, ground wires and control wires, are then placed into individual sockets in a large aluminum connector. Both ends of the cable are connected by attachment to the aluminum connector. There are two major disadvantages to the aluminum connector. First, the aluminum connector is very costly, typically costing in excess of $3,000.00. Second, the aluminum connector does not permit the multi-conductor cable to be wound back on a spool properly since the connector has a much larger diameter than the cable.
Another prior art method of splicing large multi-conductor cables includes cutting the cable at the damaged spot, nailing or retaining in some other way both ends of the damaged cable on a table or other support surface. The insulation is then peeled back and the individual conductors are pulled apart. The conductors are individually spliced by soldering or crimping using a crimping sleeve.
Since the individual conductors have been pulled apart from each other, the spliced conductors must then be brought together so that the spliced section can be properly reinsulated. The spliced portion is then placed in a mold and the exposed conductors are wrapped with insulating tape. An insulative rubber compound is then poured within the mold.
The spliced section made by the immediately-above mentioned method is often times inadequate. Since the conductors are one-inch diameter solid copper, they are difficult to handle and are not properly positioned together. A bulldozer or other heavy piece of equipment is used to lay the cable and the spliced section of the cable is subjected to great stretching forces. These forces move the individual conductors with respect to each other in the spliced area. The movement of the conductors in the cured rubber compound breaks down the insulative qualities of the rubber.
There are several prior art patents which disclose cable splicing devices for splicing multi-conductor cable. These patents include the Martin U.S. Pat. No. 2,802,489, the Brown et al U.S. Pat. No. 3,665,574, the Enright et al U.S. Pat. No. 3,713,214, and the Copas U.S. Pat. No. 3,890,689. However, none of the devices shown in these patents are suitable for holding a large diameter cable during splicing.